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        let lp1='abcdef'
        console.log(lp1.toUpperCase(''))
        let lp2='ABCDEF'
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        let lp='abcdef'
        console.log(lp.substr(3,5))
        let lan='abcdef'
        console.log(lan.slice(3,5))
        console.log(lan.slice(''))
        console.log(lan.slice('',2))
        let str='abcdef'
        console.log(str.split('f'))
        console.log(str.split(''))
        console.log(str.split('',4))
        var a="hallo word"
        var s=200
        var d=true
        var f=null
        var g=undefined
        console.log(a,s,d,f,g)
        var joke={
            name:"孙儿",
            age:22,
            hobby:"hhhh"
        }
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    <h1   id="domo">标签</h1>
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            document.getElementById("domo").innerHTML ="修改段落"
            
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